Ttk where to get?

Talk to the Blacksmith in order to perform the upgrading.

OBTAINING TIPS

MASTERY:

second sea: server hop for awakened ice admiral, as it drops the highest mastery in second sea. You can also grind Cursed Captain, although this is less effective.

Third sea: server hop for Cake queen, Island empress, or Captain Elephant, depending on your skill level. Dough King is also adviced, but very rare, and very hard to do, however rewarding.

It is advised to refund your stats into a sword main so it is easier to damage and level up the legendary swords.

MONEY:

this sword costs 8 million dollars, so money is very hard to obtain.

2x money gamepass is recommended.

second sea: grind the first three bosses (diamond, Jeremy, Fajita) by server hopping. Each server can yield 75K, 150K with 2x money. Alternatively, if you have good RNG (unlike me), you could farm sea beasts, for their insane (100-200K without 2x money) money drops. However, if you want a stable and easy money source, use the first option

Third sea: Sea Beast or Rumbling Waters hunt, as one sea beast would give 100-200k (no 2x money), and rumbling waters can give up to 1.5 MILLION with 2x money. Also, you can join a hacker-filled lobby (look for hong kong servers), and camp Drip_Mama while the hackers do the job for you. Once the portal opens, grind Cake Prince, and again, let the hackers do the dirty work, and you only needing to do 10% of the damage. It gives around 100k normally.

(No accessories, full body aura, 2450 sword stats, 600 mastery, Grade 1)

True Triple Katana is one of the four mythical swords (The other is Yoru, cursed dual katana and hallow scythe.) It is obtained by getting Saddi, Shisui and Wando. You need to get all of these swords to 300 mastery. Then, you go to the green zone to the highest leaf, and there is a NPC called the mysterious man.